Messages in this thread | | | Date | Thu, 23 Jul 2020 13:27:57 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH for 5.9 1/3] futex: introduce FUTEX_SWAP operation |
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On Wed, Jul 22, 2020 at 04:45:36PM -0700, Peter Oskolkov wrote: > This patchset is the first step to open-source this work. As explained > in the linked pdf and video, SwitchTo API has three core operations: wait, > resume, and swap (=switch). So this patchset adds a FUTEX_SWAP operation > that, in addition to FUTEX_WAIT and FUTEX_WAKE, will provide a foundation > on top of which user-space threading libraries can be built.
The PDF and video can go pound sand; you get to fully explain things here.
What worries me is how FUTEX_SWAP would interact with the future FUTEX_LOCK / FUTEX_UNLOCK. When we implement pthread_mutex with those, there's very few WAIT/WAKE left.
Also, why would we commit to an ABI without ever having seen the rest?
On another note: wake_up_process_prefer_current_cpu() is a horrific function name :/ That's half to a third of the line limit.
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